Articles with radiation cured adhesive as alternative to heat seals

ABSTRACT

A bag includes a first and second panel; first and second layflat side edges; a bottom edge; and a bag mouth; at least one of the layflat side edges, and the bottom edge, includes a radiation cured adhesive layer bonding the first and second panels together. A thermoformed container includes a forming web and a substantially non-forming web; and a radiation cured adhesive layer disposed between and bonding at least portions of the forming web and the substantially non-forming web. A film/foam composite includes a thermoplastic film and a polymeric foam sheet; and a radiation cured adhesive layer disposed between and bonding at least portions of the thermoplastic film and the polymeric foam sheet. An inflatable packaging cushion includes a plurality of flexible plastic sheets bonded together in the region of their edges; a radiation cured adhesive layer bonds at least a portion of the flexible plastic sheets together.

FIELD OF THE INVENTION

The present invention relates to a container or container component,e.g. a thermoplastic container or container component, such as a bag(e.g. for food packaging), including a containers made from acrosslinked film; a thermoformed container; a film/foam composite; or aninflatable packaging cushion; in each of which at least two plies offilm, or at least one ply of film and at least one ply of foam, arejoined together by a radiation curable adhesive.

BACKGROUND OF THE INVENTION

In many packaging applications, for food and non-food markets, films andfilm/foam combinations, such as thermoplastic films and film/foamcombinations, are widely used in making the packaging or componentsthereof.

For example, flexible film bags have been manufactured and sold for thepackaging of a wide variety of products, including fresh red meat,smoked and processed meat, etc. Examples are shown in U.S. Pat. No.6,282,869 (Bullock et al.) incorporated herein by reference in itsentirety. The film for these bags sometimes comprises a coextruded,totally irradiated and therefore crosslinked structure, and sometimes anextrusion coated material with an irradiated, crosslinked substrate andan unirradiated, uncrosslinked extrusion coating.

Thermoformed containers likewise are used in packaging many food andnon-food products, and typically include a thermoformed substrate and alidding film. Examples are shown in U.S. Pat. No. 4,729,476 (Lulham etal.) incorporated herein by reference in its entirety.

Film/foam composites are formed e.g. when a barrier liner is adhered toa foamed or solid tray, such as a polystyrene, polycarbonate, orpolyolefin tray. Examples are shown in U.S. Pat. No. 5,952,076 (Fosteret al.) incorporated herein by reference in its entirety.

Packagers are increasingly using air-inflated cushions formed fromrelatively thin films of thermoplastic to protect their packaged goodswithin boxes, sleeves, or cases during shipping and storage. See U.S.Pat. No. 5,803,263 (Pozzo), and U.S. Pat. Nos. 6,276,532 and 6,569,283(Sperry et al.), all incorporated herein by reference in their entirety.For example, an inflatable packaging cushion system that can protect awide variety of packaged goods is sold by Sealed Air Corporation underthe VISTAFLEX™ trademark. The VISTAFLEX™ inflatable packaging cushionincludes an inflation inlet designed for use with an inflation/sealingmachine provided by Sealed Air Corporation under the BT-1™ trademark.The BT-1 inflator/sealer controls both the inflation of the cushion withcompressed air and sealing of the inflated cushion with an impulse heatsealer. To inflate and seal the VISTAFLEX™ cushion, a user inserts aninflation tube into an inflation inlet of the cushion. Theinflator/sealer inflates the cushion by opening a valve to allowcompressed air to pass through the inflation tube into the interior ofthe cushion chamber until the cushion chamber has been inflated to thedesired pressure. At that point, a heat seal bar compresses the top andbottom sheets of the inlet to prevent the inflated cushion fromdeflating. An inflatable packaging cushion is a useful form ofprotective packaging for applications where the cushioning effect of thematerial offers protection of a fragile product from physical shock anddamage during shipping of the product. An object to be packaged is,after inflating the inflatable packaging cushion, intimately wedgedbetween the internal faces of the cushion which, by its deformability,adapts to the shape and/or size of the object. Thus, such a packagingitem can be used for packaging articles of various dimensions and shapesby suitably wedging them each time.

Common to these packaging formats is a heat-sealing process, oralternative adhesion techniques such as radio frequency sealing, gluing,etc. to join films or film plies together, or to join film or film pliesto one or more foam plies. In the case of flexible bags, a “factoryseal” is typically made, referring to any and all seals necessary toconvert a film tubing or flat film into a bag having an open end. Suchseals are usually made at a bag-making factory, rather than at locationat which products are being packaged.

Heat sealing of certain polymeric materials can be difficult andrelatively slow. In the case of dissimilar materials, heat sensitivematerials (such as some foams), or crosslinked materials, heat sealingcan sometimes become so technically difficult or impossible as to becommercially unfeasible. Heat can degrade some foam materials.

In the case of heat shrinkable films, heat sealing frequently results insome degree of puckering of the film material in the area of the heatseal, triggered of course by the application of heat to the seal area ofthe package. This phenomenon can degrade the aesthetics of the package,and in extreme cases make the package unusable from a commercialviewpoint.

Also, where intricate sealing patterns, geometries, or profiles aredesired, or else dictated by the shape of the package, e.g. in the caseof an inflatable packaging cushion, it can be difficult and expensive todesign heat seal tooling that will adequately and reliably create thepatterns.

In accordance with the present invention, radiation curable adhesivescan be used to bond together films or film and foam, in the productionof a containers or container component, e.g. a thermoplastic containersor container component, such as a bag (e.g. for food packaging),including a container made from a crosslinked film; a thermoformedcontainer; a film/foam composite; or an inflatable cushioning material;in each of which at least two plies of film, or at least one ply of filmand at least one ply of foam, are to be joined together.

SUMMARY OF THE INVENTION

In a first aspect of the invention, a bag comprises a first panel; asecond panel; first and second layflat side edges; a bottom edge; and abag mouth; wherein at least one of the first and second layflat sideedges, and the bottom edge, comprises a radiation cured adhesive layerbonding the first and second panels together.

In a second aspect of the invention, a thermoformed container comprisesa forming web, the forming web comprising a polymeric material; asubstantially non-forming web comprising a polymeric material; and aradiation cured adhesive layer disposed between and bonding at leastportions of the forming web and the substantially non-forming web.

In a third aspect of the invention, a film/foam composite comprises athermoplastic film comprising a polymeric material; a polymeric foamsheet; and a radiation cured adhesive layer disposed between and bondingat least portions of the thermoplastic film and the polymeric foamsheet.

In a fourth aspect of the invention, an inflatable packaging cushioncomprises a plurality of flexible plastic sheets bonded together in theregion of their edges, wherein a radiation cured adhesive layer bonds atleast a portion of the flexible plastic sheets together.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of embodiments of the invention follows, withreference to the attached drawings, wherein:

FIG. 1 is a schematic of an end-seal bag in lay-flat view;

FIG. 2 is a cross-sectional view through section 2-2 of FIG. 1;

FIG. 3 is a schematic of a side-seal bag in lay-flat view;

FIG. 4 is a cross-sectional view through section 4-4 of FIG. 3;

FIG. 5 is a fragmentary cross-sectional view through section 5-5 of FIG.1;

FIG. 6 is a fragmentary cross-sectional view of an side seal of FIG. 4;

FIG. 7 is a schematic of a process and apparatus for making a filmuseful in the invention;

FIG. 8 is a schematic cross-sectional view of a film useful with theinvention;

FIG. 9 is a schematic cross-sectional view of a film useful with theinvention; FIG. 10 is a plan view of a thermoformed container of theinvention;

FIG. 11 is a side view of the container of FIG. 10;

FIG. 12 is a cross-sectional view taken along line XII-XII of FIG. 10;

FIG. 13 is an enlarged cross-sectional view of the container of FIG. 12;

FIG. 14 is a schematic cross-sectional view of a film/foam composite ofthe invention;

FIG. 15 is a schematic of a process and apparatus for making a film/foamcomposite of the invention;

FIG. 16 is a plan view of a first embodiment of an inflatable cushion inaccordance with the invention, in the deflated state;

FIG. 17 is a plan view of the inflatable cushion of FIG. 16, in theinflated state;

FIG. 18 is a perspective view of the inflatable cushion of FIG. 16, inthe inflated state;

FIG. 19 is a plan view of a first alternative embodiment of theinflatable cushion of FIG. 16, in the deflated state;

FIG. 20 is a plan view of a second alternative embodiment of theinflatable cushion of FIG. 16, in the deflated state;

FIG. 21 is a plan view of an inflatable cushion according to theinvention, in the deflated state, comprising a self-sealing valve in acorner;

FIG. 22 is a sectional view along line A-A′ of the self-sealing valve ina corner of the inflatable cushion of FIG. 21;

FIG. 23 is a detailed view of the self-sealing value in a corner and oftwo tabs for guiding the inflatable cushion of FIG. 21;

FIG. 24 is a sectional view along line B-B′ of the valve and of the twotabs of FIG. 23;

FIG. 25 is a detailed view of an alternative embodiment of theself-sealing valve of FIG. 21;

FIG. 26 is a schematic view of an apparatus and process for making a bagof the invention;

FIG. 27 is a plan view of a web printed with a patterned seal design;

FIG. 28 is a plan view of the printed web of FIG. 27 after lamination toa second web; and

FIG. 29 is a plan view of a waste web resulting from the process of theinvention.

Definitions

As used herein, the term:

“abuse layer” and the like refers to an outer film layer and/or an innerfilm layer, so long as the film layer serves to resist abrasion,puncture, and other potential causes of reduction of package integrity,as well as potential causes of reduction of package appearance quality.Abuse layers can comprise any polymer, so long as the polymercontributes to achieving an integrity goal and/or an appearance goal;examples include ethylene/alpha-olefin copolymer having a density offrom about 0.85 to 0.95, propylene/ethylene copolymer, polyamide,ethylene/vinyl acetate copolymer, ethylene/methyl acrylate copolymer,and ethylene/butyl acrylate copolymer, etc.

“barrier” as applied to films and/or film layers, refers to the abilityof a film or film layer to serve as a barrier to one or more gases.Barrier materials have an oxygen permeability, of the barrier material,less than 500 cm³ O₂/m²·day·atmosphere (tested at 1 mil thick and at 25°C. according to ASTM D3985), such as less than 100, less than 50 andless than 25 cm³O₂/m²·day·atmosphere such as less than 10, less than 5,and less than 1 cm³O₂/m²·day·atmosphere. Examples of polymeric materialswith low oxygen transmission rates are ethylene/vinyl alcohol copolymer(EVOH), polyvinylidene dichloride (PVDC), vinylidene chloride/methylacrylate copolymer, polyamide, polyester, metal foil, SiO_(x) compounds,and metallized foils such as a sputter coating or other application of ametal layer to a polymeric substrate such as high density polyethylene(HDPE), ethylene/vinyl alcohol copolymer (EVOH), polypropylene (PP),polyethylene terephthalate (PET), polyethylene naphthalate (PEN), orpolyamide (PA). Even a sufficiently thick layer of a polyolefin such asLLDPE, or PVC (polyvinyl chloride) can in some instances provide asufficiently low oxygen transmission rate for the overall film for itsintended function. The exact oxygen permeability optimally required fora given application can readily be determined through experimentation byone skilled in the art.

“bonding layer” and the like refers to an outermost film layer (or thesingle layer of a monolayer film) involved in the bonding of the film toitself, to another film layer of the same or another film, and/oranother article or container component which is not a film. can compriseany thermoplastic polymer.

“bulk layer” refers to any layer of a film which is present for thepurpose of increasing the abuse-resistance, toughness, modulus, etc., ofa multilayer film. Bulk layers can comprise polymers which areinexpensive relative to other polymers in the film, and/or which providesome specific purpose unrelated to abuse-resistance, modulus, etc.Examples include polyolefin; ethylene/alpha-olefin copolymer, lowdensity polyethylene, and linear low density polyethylene.

“ethylene/alpha-olefin copolymer” (EAO) refers to copolymers of ethylenewith one or more comonomers selected from C₃ to C₁₀ alpha-olefins suchas propene, butene-1, hexene-1, octene-1, etc. in which the molecules ofthe copolymers comprise long polymer chains with relatively few sidechain branches arising from the alpha-olefin which was reacted withethylene. This molecular structure is to be contrasted with conventionalhigh pressure low or medium density polyethylenes which are highlybranched with respect to EAOs and which high pressure polyethylenescontain both long chain and short chain branches. EAO includes suchheterogeneous materials as linear medium density polyethylene (LMDPE),linear low density polyethylene (LLDPE), and very low and ultra lowdensity polyethylene (VLDPE and ULDPE), such as DOWLEX™ or ATTANE™resins supplied by Dow, and ESCORENE™ or EXCEED™ resins supplied byExxon; as well as linear homogeneous ethylene/alpha olefin copolymers(HEAO) such as TAFMER™ resins supplied by Mitsui PetrochemicalCorporation, EXAC™ resins supplied by Exxon, or long chain branched(HEAO) AFFINITY™ resins supplied by the Dow Chemical Company, or ENGAGE™resins supplied by DuPont Dow Elastomers.

“ethylene homopolymer or copolymer” herein refers to ethylenehomopolymer such as low density polyethylene; ethylene/alpha olefincopolymer such as those defined herein; ethylene/vinyl acetatecopolymer; ethylene/alkyl acrylate copolymer; ethylene/(meth)acrylicacid copolymer; or ionomer resin.

“film” and the like refers to plastic web, regardless of whether it isfilm or sheet. Films used in the present invention have a thickness of0.5 to 40 mils.

“oriented” refers to a polymer-containing material which has beenstretched at an elevated temperature (the orientation temperature),followed by being “set” in the stretched configuration by cooling thematerial while substantially retaining the stretched dimensions. Uponsubsequently heating unrestrained, unannealed, orientedpolymer-containing material to its orientation temperature, heatshrinkage is produced almost to the original unstretched, i.e.,pre-oriented dimensions. More particularly, the term “oriented”, as usedherein, refers to oriented films, wherein the orientation can beproduced in one or more of a variety of manners.

“polymer” refers to the product of a polymerization reaction, and isinclusive of homopolymers, copolymers, terpolymers, etc.

“polyolefin” refers to any polymerized olefin, which can be linear,branched, cyclic, aliphatic, aromatic, substituted, or unsubstituted.Specific examples include polyethylene homopolymer, polypropylenehomopolymer, polybutene, ethylene/alpha-olefin copolymer,propylene/alpha-olefin copolymer, butene/alpha-olefin copolymer,ethylene/vinyl acetate copolymer, ethylene/ethyl acrylate copolymer,ethylene/butyl acrylate copolymer, ethylene/methyl acrylate copolymer,ethylene/acrylic acid copolymer, ethylene/methacrylic acid copolymer,modified polyolefin resin, ionomer resin, polymethylpentene, etc.

“tie layer” refers to any internal layer having the primary purpose ofadhering two layers to one another. Tie layers can comprise any polymerhaving a polar group grafted thereon, so that the polymer is capable ofcovalent bonding to polar polymers such as polyamide and ethylene/vinylalcohol copolymer. Tie layers can comprise polyolefin, modifiedpolyolefin, ethylene/vinyl acetate copolymer, modified ethylene/vinylacetate copolymer, and homogeneous ethylene/alpha-olefin copolymer;anhydride modified grafted linear low density polyethylene, anhydridegrafted low density polyethylene, homogeneous ethylene/alpha-olefincopolymer, and anhydride grafted ethylene/vinyl acetate copolymer.

All compositional percentages used herein are presented on a “by weight”basis, unless designated otherwise.

DETAILED DESCRIPTION OF THE INVENTION

Bags: Article

Film in the form of seamless tubing can be converted into end-seal bags.FIG. 1 is a lay-flat view of a end-seal bag 10 of the present invention.End-seal bag 10 is made from seamless tubular film 12, and has a bagmouth 14, first and second lay-flat side edges 16 and 18, bottom edge20, and end-seal 22. FIG. 2 illustrates a cross-sectional view ofend-seal bag 10 taken through section 2—2 of FIG. 1.

In the end-seal bag, therefore, the side edges of the bag are actuallyformed by lay flat folds in the seamless tubing. The bottom edge of thebag is a cut in the tubing that is closed by the application of aradiation curable adhesive to the internal surface of the bottom portionof either or both of first and second panels (24 and 26) of the bag. Theradiation curable adhesive is thus disposed between the bottom portionsof the front and rear panels (24 and 26) of the bag. The radiationcurable adhesive is cured as disclosed herein to bond together theseportions. FIG. 5 shows a fragmentary enlarged cross sectional view ofthe end seal 22. A radiation cured adhesive layer or region 42 bondstogether the internal surfaces of first panel 24 and second panel 26.Although shown in FIG. 5 as a continuous layer, the radiation curedadhesive layer can alternatively be discontinuous in nature, disposed inselected regions but not continuously across the width of the bottomseal 22 of the bag 10. The radiation cured adhesive layer can also varyin its vertical extent along the seal (vertical as viewed in the planview of FIG. 1). Finally, the thickness or depth of the radiation curedadhesive layer, although shown in FIG. 5 as of uniform thickness, canvary in thickness either within one applied coat of adhesive, or bymeans of multiple coats of adhesive in selected regions of the overallseal area.

Alternatively, film in the form of seamless tubing can be converted intoside-seal bags. FIG. 3 is a lay-flat view of side-seal bag 30 of thepresent invention. Side-seal bag 30 is made from dual-seamed tubularfilm 32, and has open top 34, first and second side seals 36 and 38, andbottom edge 40. FIG. 4 is a cross-sectional view of side-seal bag 30,taken through section 4-4 of FIG. 3.

In the side-seal bag, therefore, the bottom edge of the bag is actuallyformed by a lay flat fold in the seamless tubing. The side edges of thebag are cuts in the tubing that are closed by the application of aradiation curable adhesive to the internal surface of the side edgeportions of either or both of front and rear panels (44 and 46) of thebag. The radiation curable adhesive is thus disposed between the sideedge portions of the front and rear panels (44 and 46) of the bag. Theradiation curable adhesive is cured as disclosed herein to bond togetherthese portions. FIG. 6 shows a fragmentary enlarged cross sectional viewof the side seal 36. A radiation cured adhesive layer or region 48 bondstogether the internal surfaces of first panel 44 and second panel 46.Although shown in FIG. 6 as a continuous layer, the radiation curedadhesive layer can alternatively be discontinuous in nature, disposed inselected regions but not continuously across the length of the side seal36 of the bag 30. The radiation cured adhesive layer can also vary inits lateral extent along the seal (lateral as viewed in the plan view ofFIG. 3). Finally, the thickness or depth of the radiation cured adhesivelayer, although shown in FIG. 6 as of substantially uniform thickness,can vary in thickness either within one applied coat of adhesive, or bymeans of multiple coats of adhesive in selected regions of the overallseal area.

The teaching herein relating to side seal 36, and alternativeembodiments thereof, apply mutatis mutandis to side seal 38.

Bags: Process

The bags of the invention as described herein are made fromthermoplastic film. Film for the production of the bags as describedherein can be produced by any suitable method, e.g. in accordance with aprocess schematically illustrated in FIG. 7. In the process illustratedin FIG. 7, solid polymer beads (not illustrated) are fed to one or aplurality of extruders 29 (for simplicity, only one extruder isillustrated). Inside extruders 29, the polymer beads are forwarded,melted, and degassed, following which the resulting bubble-free melt isforwarded into die head 31, and extruded through an annular die,resulting in tubing 33 which can be of any suitable thickness, e.g. 5 to25 mils thick. After cooling or quenching by water spray from coolingring 35, tubing 33 is collapsed by pinch rolls 37, and is thereafter fedthrough irradiation vault 39 surrounded by shielding 41, where tubing 33is irradiated with high energy electrons (i.e., ionizing radiation) fromiron core transformer accelerator 43. Tubing 33 is guided throughirradiation vault 39 on rolls 45. Tubing 33 is irradiated to a level ofe.g. from 10 to 70 kiloGrays. After irradiation, irradiated tubing 47 isdirected through pinch rolls 49, following which irradiated tubing 47 isslightly inflated, resulting in trapped bubble 50. However, at trappedbubble 50, the tubing is not significantly drawn longitudinally, as thesurface speed of nip rolls 52 are about the same speed as nip rolls 49.Furthermore, irradiated tubing 47 is inflated only enough to provide asubstantially circular tubing without significant transverseorientation, i.e., without stretching. Slightly inflated, irradiatedtubing 50 is passed through vacuum chamber 54, and thereafter forwardedthrough coating die 56. Second tubular film 58 is melt extruded fromcoating die 56 and coated onto slightly inflated, irradiated tube 50, toform two-ply tubular film 60. Second tubular film 58 can comprise anoxygen-barrier layer, which does not pass through the ionizingradiation. Further details of the above-described coating step aregenerally as set forth in U.S. Pat. No. 4,278,738, to BRAX et. al.,which is hereby incorporated by reference thereto, in its entirety.

After irradiation and coating, two-ply tubing film 60 is wound up ontowindup roll 62. Thereafter, windup roll 62 is removed and installed asunwind roll 64, on a second stage in the process of making the tubingfilm as ultimately desired. Two-ply tubular film 60, from unwind roll64, is unwound and passed over guide roll 66, after which two-plytubular film 60 passes into hot water bath tank 68 containing hot water70. The now collapsed, irradiated, coated tubular film 60 is submersedin hot water 70 (having a temperature of e.g. 185.degree. F.) for aretention time of at least about 30 seconds, i.e., for a time period inorder to bring the film up to the desired temperature for biaxialorientation. Thereafter, irradiated tubular film 60 is directed throughnip rolls 72, and bubble 74 is blown, thereby transversely stretchingtubular film 60. Furthermore, while being blown, i.e., transverselystretched, nip rolls 76 draw tubular film 60 in the longitudinaldirection, as nip rolls 76 have a surface speed higher than the surfacespeed of nip rolls 72. As a result of the transverse stretching andlongitudinal drawing, irradiated, coated biaxially-oriented blown tubingfilm 78 is produced, this blown tubing having been both transverselystretched in a ratio of e.g. from 1:1.5 to 1:6, and drawn longitudinallyin a ratio of e.g. from 1:1.5 to 1:6. Alternative ratios are from 1:2 to1:4 (transverse direction) and from 1:2 to 1:4 (longitudinal direction).

While bubble 74 is maintained between pinch rolls 72 and 76, blowntubing 78 is collapsed by rolls 80, and thereafter conveyed throughpinch rolls 76 and across guide roll 82, and then rolled onto wind-uproll 84. Roll 86 assures a good wind-up.

Those skilled in the art will understand that many variations in theabove film making process can offer alternative processing. For example,a full coextrusion process can be used instead of an extrusion coatingprocess, particularly where polymeric materials compatible with theirradiation process are used, or where the film is not irradiated. Flatcast extrusion can be used, followed by standard tenterframingtechniques to accomplish orientation of the film. Bags can then be madeby back seaming and end sealing methods well known in the art, but withthe use of radiation curable adhesives in place of heat sealing.Monoaxial orientation can be employed, or the film can remainunoriented, that is, not stretch oriented as described above.Irradiation can alternatively be employed after the film has been fullycoextruded.

It should also be noted that radiation curable adhesives can be used toproduce one or more seals of a bag with multiple seals, and heat sealingor another alternative sealing mechanism (adhesive, glue, radiofrequency sealing, ultrasonic sealing, etc.) can be used to produce oneor more of the remaining seals of the bag.

End seal and side seal bags can then be made from the biaxially-orientedblown tubing film.

Referring to FIGS. 26 through 29, two polymeric film webs 122 and 124are fed, from feed rolls 126 and 128 respectively into individual hauloff nip rolls 130 and 132 respectively whereby the film webs are unwoundfrom rolls 126 and 128. Web 126 is advanced through a printing process134, whereby the predetermined pattern 135 of the radiation curableadhesive and the seal or weld that will result therefrom after curing)is printed on a surface of web 126 with a radiation curable adhesive.FIG. 27 is a view of web 126 after printing. The two webs 122 and 124are then brought together at the juncture of rolls 136 and 138 (see FIG.28). Just prior to that joining, the radiation curable adhesive isexposed to a dose of ultraviolet light, at station 140, effective tocure the radiation curable adhesive and thereby bond the two webstogether at points on the respective webs contacted by the pattern 135.Immediately after the exposure, the two webs are conveyed by a set ofnip rollers 142 a and 142 b.

The joined webs are then advanced, e.g. by conveyor, to a station 146where the predetermined pattern 135 of each bag is cut. This can beaccomplished by means of an intermittent operation using a flat steelrule die, or a rotary steel rule die 148 against a rotary steel anvil150. The waste web 152 is then conveyed away (see FIG. 29), while theindividual bags are then laid in imbricated (shingled) fashion onconveyor 156. Waste web 152 in this embodiment will exhibit patternedholes 153 reflecting the conformation of the bags cut from the web.

In an alternative embodiment, a tubular web can be single edge slit andunfolded to provide one of the webs described hereinabove with respectto the process of FIG. 26; or the tubular web can be edge slit and plyseparated into two separate flat webs that can then function as each ofthe webs disclosed in connection with FIG. 26.

Films useful in connection with the invention can be monolayer films ormultilayer films. If multilayer, the film can have any suitable numberof layers, such as a total of from 2 to 20 layers.

In general, the film can have any total thickness desired, and eachlayer can have any thickness desired, so long as the film provides thedesired properties for the particular packaging operation in which thefilm is used, e.g. abuse-resistance (especially puncture-resistance),modulus, optics, oxygen barrier properties, etc.

Each layer of the film can be made from any suitable polymeric material,such as any suitable thermoplastic polymer or copolymer, such aspolyolefin (e.g. ethylene/alpha-olefin copolymer), ethylene copolymer,polyamide, polyester, polyvinyl chloride, polypropylene,ethylene/propylene copolymer, homopolymers of ethylene, ethylenecopolymers having at least 50 mole percent of an ethylene unit and aminor proportion of a monomer copolymerizable with ethylene, such asvinyl acetate, vinyl chloride, propylene, butene, hexene, acrylic acidand its esters, and methacrylic acid and its esters; polybutadiene.Examples of polyethylenic resins which can be advantageously employedinclude the invention are low-, medium- and high-density polyethylenes,and copolymers thereof.

FIGS. 2, 4, 5, and 6 depict a monolayer film. This monolayer film cancomprise any suitable polymer, such as those listed above. Instead of amonolayer film, a multilayer film can be provided to make bags of theinstant invention.

By way of example, FIG. 3 shows a two layer film 88. Layer 89 is a layerthat can be used as the bonding layer, to be joined to a like layer in aseamless tube, or to another layer of this or another film. The layersthat make up the bonding layers of a bag of the invention can be thesame or different either chemically or physically. Layer 90 is a secondlayer. Layers 88 and 89 can also contain appropriate amounts of otheradditives, such as slip agents such as talc, antioxidants, fillers,dyes, pigments and dyes, radiation stabilizers, antistatic agents,elastomers, and the like additives known to those of skill in the art ofpackaging films.

A multilayer film of the invention can have one or more internal orexternal film layers which have a primary function as an adhesive orcompatibilizer (tie layer) for adhering two layers to one another; orprovide abuse resistance, oxygen barrier, or other functionality.Usually, the core layer or layers provide the multilayer film with adesired level of strength, i.e., modulus, and/or optics, and/or addedabuse resistance, and/or specific impermeability.

The multilayer films used in the present invention are optionallyirradiated, before bag making and in some cases before orientation, toinduce crosslinking. In the irradiation process, the film is subjectedto an energetic radiation treatment, such as corona discharge, plasma,flame, ultraviolet, X-ray, gamma ray, beta ray, and high energy electrontreatment, which induces cross-linking between molecules of theirradiated material. The irradiation of polymeric films is disclosed inU.S. Pat. No. 4,064,296, to BORNSTEIN, et. al., which is herebyincorporated in its entirety, by reference thereto. Radiation suppliedto cure a radiation curable adhesive can also function to irradiate thefilm layers to induce cross-linking.

Thermoformed Container

Referring to FIGS. 10 to 13, container 250 has a first web 252 which isa forming web produced by thermoforming or other suitable techniqueswell known in the art. Suitable thermoforming methods, for example,include a vacuum forming or plug-assist vacuum forming method. In avacuum forming method, the first web is heated e.g. by a contact heaterand a vacuum is applied beneath the web causing the web to be pushed byatmospheric pressure down into a pre-formed mold. In a plug-assistvacuum forming method, after the first or forming web has been heatedand sealed across a mold cavity, a plug shape similar to the mold shapeimpinges on the forming web and, upon the application of vacuum, theforming web transfers to the mold surface.

After the first web is in place, a product 254, such as a smoked sausageor other food or non-food product, is placed, such as by manual loading,on the first web. Either before, during, or after the step of placingthe product 254 on the first web, a radiation curable adhesive isapplied in either a continuous or discontinuous fashion in theperipheral area of the first web, on the surface of the first web thatwill be subsequently contacted by the peripheral area of a second web256. The second, substantially non-forming web 256 is disposed over theproduct and the first web with the radiation curable adhesive disposedon the first web. A release of vacuum then causes the second web 256 totack to the first web 252 so as to enclose the product between the websand self-weld the first and second webs at their contiguous surfaces.

The radiation curable adhesive forms an intermediate layer 260 in theresulting package. The container is thereafter subjected to UV, electronbeam, or other radiation sufficient to cure the adhesive and create abond between the first web 252 and the second web 256. The radiationcurable adhesive layer 260 thus becomes a bonding layer comprising aradiation cured adhesive.

Alternatively, the radiation curable adhesive can be applied in either acontinuous or discontinuous fashion in the peripheral area of the secondweb (instead of the first web), on the surface of the second web thatwill be subsequently contacted by the peripheral area of the first web252. In still another alternative, the radiation curable adhesive can beapplied in either a continuous or discontinuous fashion in theperipheral area of both the first and second webs.

After the first and second webs 252 and 256 have been self-welded, andpreferably before the shrinking operation described above is performed,the peripheral edge of the package is sealed or bonded by a radiationcurable adhesive. This peripheral seal 260 is located at or near theactual periphery of the package.

Although the first and second webs 252 and 256 are depicted in FIG. 13as being of monolayer construction, like the films described herein,these webs can be of multilayer construction, each layer comprising anysuitable polymer such as those disclosed herein; of any suitablethickness; and made by any suitable process.

Film/Foam Composite

In FIG. 14, a film/foam composite 310 includes bottom film 311 and topfoam sheet 312. Bottom film 311 comprises any suitable polymer such asthose disclosed herein. Top foam sheet 312 comprises any suitable foammaterial, e.g. low density polyethylene foam having a density of about 2pcf. In laminate 310, top foam sheet 312 and bottom film 311 are adheredtogether by means of a radiation curable adhesive layer 313. Thepolyethylene foam can be extruded in sheet form and then laminated tothe polyethylene film.

One process of preparing the film/foam composite involves bringingtogether a moving continuous web of a thin sheet of polyethylene foamand a moving continuous web of the bottom film 311, as shown in FIG. 15.A radiation curable adhesive 323 is stored in a container 322, andapplied from a nozzle 321 to one or both of the facing surfaces of themoving webs at the point of contact between the moving webs, to formradiation curable adhesive layer 313. The webs are then brought togetherby e.g. applying pressure by two opposing rollers 324 and 325 to thecontacting webs at the point of contact of the moving webs. A radiationcuring unit 326, e.g. a UV unit, is positioned downstream on one or bothsides of the composite to achieve bonding of webs 311 and 312 togetherand transform radiation curable adhesive layer 313 to radiation curedadhesive layer 313. Although bottom film 311 is shown as a monolayerfilm, it can comprise two or more layers as disclosed herein.

The nip pressure applied by the opposed rollers on the laminate istypically between 0 to 10 pcf and about 150 pcf, e.g. about 60 pcf.

The moving continuous web of top foam sheet 312 can be formed byextrusion, passed through at least one oven, and, while being at atemperature between 350.degree. F. and 500.degree. F., brought intocontact with the moving continuous web of bottom film 311. The rollerscan be chilling rollers.

The foam sheet can be that obtained from a third party or manufacturedon site and later used, but in either case the foam sheet can bereheated just before it is laminated with the polyethylene film. Thelamination can be done using extruded foam sheet at an elevatedtemperature immediately after exiting the oven(s) downstream from theextruder.

Typically, polyethylene films are 10 mils thick or less, andpolyethylene sheets are greater than 10 mils thick.

The foam sheet 312 can be formed by means of a conventional polyethylenefoam sheet extrusion process or any other suitable foam sheet-formingprocess. The foam sheet can be open or closed celled.

The bottom film 311 can be formed by means of a conventional filmextrusion process or any other suitable film-forming process.

If the bottom film 311 comprises a heat shrinkable material, made byorientation techniques well known in the art, and if the radiationcurable adhesive is applied at specific intermittent points along theinterface between the bottom film 311 and top foam sheet 312, then uponthe application of sufficient heat, the composite will deform to anundulating structure.

Inflatable Packaging Cushion

Referring to FIGS. 16, 17 and 18, these show a first embodiment of aninflatable packaging cushion 100 of the invention, intended to wedge andto protect one or more objects to be packaged.

This inflatable cushion 100 includes an external peripheral edge 101which here describes essentially a rectangle and which is generallyadapted to the shape and to the dimension of a packaging receptacle, forexample a box made from rigid cardboard; a trayed package including atray, a product disposed in the tray, and a lidstock sealed to the topof the tray; or the like. This inflatable cushion 100 includes aninternal opening 102, which is rectangular for example, capable ofreceiving at least one object 500 to be packaged and a plurality ofrecesses 103, here four recesses 103 extending from each of the cornersof the rectangular internal opening 102 towards the peripheral edge 101of the said cushion 100 and more precisely in the direction of thecorners of the said peripheral edge 101. As shown in FIGS. 16, 17 and18, the inflatable cushion 100 includes two sheets of flexible plastic(of any suitable polymer or blend of polymers as disclosed herein),juxtaposed and bonded together in the region of their edges along thebonding lines LS.

As seen in FIGS. 17 and 18, the recesses 103 delimit, in pairs, wedgingparts 104, 105, 106, 107, here four wedging parts capable of coming intocontact with the object 500 to be packaged, by pivoting aroundpreferential pivoting zones 108 defined between the recesses 103 and theperipheral edge 101.

The pivoting of the wedging parts 104, 105, 106, 107 around thepreferential pivoting zones 108 enables the size and/or the shape of theinternal opening 102 to be varied in order to adapt it to objects ofvarious sizes and/or shapes, whilst exerting a holding pressure on theobject or objects to be packaged by virtue of a return movement which isexerted in the region of the pivoting zones 108. In this case, the shapeof each recess 103 and/or of the peripheral edge 101 is such that, inthis region, two preferential pivoting zones 108 are locatedrespectively at two locations where the space between the recess 103 andthe external peripheral edge 101 of the cushion 100 is the least. Inthis example, the peripheral edge 101 is substantially straight betweentwo corners and each recess 103 is substantially droplet shaped, that isto say has a shape constituted by two lines 103 b, 103 c diverging froma corner of the internal opening 102 towards the peripheral edge 101 andjoined together by a rounded portion 103 a in the vicinity of this edge.In the region of the rounded portion 103 a, there are two locationswhere the space between the recess 103 and the external peripheral edge101 is the least and these two locations define two preferentialpivoting zones 108. The shapes of the recesses 103 and/or of theperipheral edge 101 which are described are not unique and the personskilled in the art will be able to make modifications to them, knowingthat it suffices to create, between one recess 103 and the peripheraledge 101, at least one narrowing so as to define at least onepreferential pivoting zone 108.

The external peripheral edge 101 can have indentations in the region ofeach recess 103 in order to define, with the recess, the preferentialpivoting zones 108. As may be better seen in FIG. 18, the shape and thedimension of the recesses 103 and of the peripheral edge 101 are suchthat, during the inflating, two neighboring wedging parts spontaneouslypivot in opposite directions, this spontaneous pivoting being due inparticular to the fact that the inflating of the cushion will generatecertain tensions in its material, especially in the neighboring regionof the recesses, and that these tensions are at a minimum after such apivoting has occurred.

The four lateral intersecting edges of the object 500 placed in theinflatable cushion 100 are engaged in the recesses 103; they are not incontact with the cushion, which minimizes the risk of wear or ofdeterioration of the cushion by these intersecting edges. The recessesconstitute, by virtue of their deformability, preferentialimpact-damping zones.

The inflatable cushion 100 shown in FIGS. 16, 17 and 18 has aself-sealing inflating valve 109 located on one side of the peripheraledge 101, enabling the cushion to be inflated or deflated by means of aninflating hose which is inserted into the valve. This inflating valve109 can be placed equally on any edge of the cushion 100 and, forexample, on the edge of the internal opening 102, emerging naturallytowards the interior of the opening. FIG. 19 shows an alternativeembodiment of the inflatable cushion 100 of FIG. 16, which here includestwo internal openings 102, 102′ of square shape. It comprises eightrecesses 103, 103′ which extend from each of the corners of each squareinternal opening 102, 102′ towards the peripheral edge 101 of thecushion 100. The cushion includes four flats beveled at the fourcorners. The internal openings 102, 102′ are placed such that eachopening 102, 102′ comprises two recesses 103, 103′ extending in thedirection respectively of two corners of the peripheral edge 101 and tworecesses 103, 103′ extending respectively towards the centers of thelongitudinal parts 101 a, 101 b of the peripheral edge 101. The cushion100 shown in FIG. 19 then comprises eight pivoting wedging parts 104,105, 106, 107, 104′, 105′, 106′, 107′ each defined by two successiverecesses, the wedging parts being capable of coming into contact withone or more objects to be packaged. Moreover, as may be seen in FIG. 19,the cushion 100 comprises a fixed central wedging part 110 which extendsbetween the openings 102, 102′ and which includes a central hole 117,produced by cutting the two sheets forming the cushion and bonding thecut edges of the sheets along the line LS. This circularly-shapedcentral hole makes it possible to act as an impact-absorbing buffer whenthe cushion is placed between the face of a packing box and an object tobe packaged. In addition, this circular hole 117 enables the thicknessof the cushion in the inflated state to be limited.

FIG. 20 shows another alternative embodiment of the inflatable cushion100 of FIG. 16, which includes two internal openings 102, 102′ eachhaving an essentially straight shape. The internal openings 102, 102′arranged in parallel have a recess 103, 103′ at each end. The cushion100 then includes four recesses 103, 103′, each of the recessesextending in the direction of a corner of the peripheral edge 101. Thecushion 100 comprises three wedging parts 104, 104′, 105. Two of thewedging parts 104, 104′ can pivot and each is delimited by the tworecesses 103, 103′ extending from the openings. The third wedging partis a fixed central part 105 lying between the two openings 102, 102′.The cushion 100 includes at the center of the central wedging part 105,two circular holes 117 which make it possible to limit the thickness ofthe inflated cushion and to act as an impact absorber. In the samemanner as for the cushion of FIG. 19, the four corners of this cushionhave a beveled flat area.

FIG. 21 shows another inflatable cushion 200. Cushion 200 is designed tobe inserted into a packaging item such as a box having articulatedclosure flaps adjacent, by one of their edges, to a corner of the box,as well as an inflatable cushion 100 of the type shown in FIGS. 16, 17,18, 19 and 20.

In FIG. 21, the inflatable cushion 200 comprises two sheets 220 offlexible plastic, bonded together in the region of their edges along thebonding line LS. As may be seen in FIG. 21, the inflatable cushion 200has a rectangular shape adapting to the shape and to the dimension of abox. This cushion shape is suitable for packing receptacles haveessentially parallelepipedal shapes. The inflatable cushion 200 caninclude a self-sealing inflating valve 210 located in a corner region ofthe cushion 200. When the latter is installed in a box, the inflatingvalve 210 is placed in the region of a corner of the box, which enablesthe cushion 200 to be inflated from outside, after closing thearticulated flaps, by means of an inflating hose 400 inserted into thevalve 210. This inflating characteristic enables a packing box havingflaps to be used without any particular arrangement for allowing thehose to pass.

As may be seen in FIGS. 21, 22 and 23, the self-sealing inflating valve210 comprises two thin sheets 211 of plastic juxtaposed and bondedtogether along two parallel lines so as to form a passage conduit forthe inflating hose 400, open at both ends. As may be better seen in FIG.22, the inflating valve 210 is located between the two sheets 220forming the cushion 200 in the corner region of the cushion.Furthermore, the valve, as FIG. 21 shows, extends from a corner of thecushion only along a part of the length of one diagonal of the cushion,which enables the cushion to be deflated by inserting the hose 400 intothe valve beyond the free end of the passage conduit.

According to a variant of the self-sealing inflating valve 210 shown inFIG. 23, the parallel bonding lines of the two thin sheets 211 moveapart locally such that the passage conduit for the inflating hosecreated by the lines includes a widening located some distance from thefree end of the conduit placed inside the cushion 200.

Thus, when the inflating of the cushion 200 is stopped and when the hose400 is still partially engaged in the passage conduit, the two thinsheets 211 are applied mutually against each other by virtue of adistortion caused in the vicinity of the free end of the conduit by thewidening, so as immediately to obstruct the conduit and thus prevent thecushion from partially deflating. In addition, as FIGS. 21, 23, 24 and25 show, the sheets 211 are bonded together at one of their ends and atthe two sheets 220 forming the cushion along a bonding line 212 aextending along a beveled flat 212 of the corner of the cushion, therebyleaving a non-bonded zone in line with an adjacent opening 215 of theconduit in order to allow the conduit to be open to the outside forinserting the inflating hose 400.

In order to facilitate the insertion of the hose into the conduit, thereis provision, as may be seen in FIGS. 21, 23, 24 and 25, for theinflatable cushion to include two flexible guide tabs 213, each of whichis constituted by the prolongation, in superposition, of a sheet 220 ofthe cushion and of a sheet 211 of the valve. As shown in FIGS. 23 and24, a peripheral bond 212 b, separate form the bonding line 212 a alongthe beveled flat 212, firmly attaches these sheets together and hasedges located in the prolongation of the adjacent edges of the cushion200. As may be seen in FIGS. 23, 24 and 25, the end of the inflatingvalve is bonded to the cushion along a bonding line 212 a, this bondlinking, on the one hand, the two thin sheets 211 and the two sheets 220constituting the cushion. Alternatively, as shown in FIG. 25, a singlebonding line 212 a′ can be seen, which extends along the beveled flat212 and which makes it possible, on the one hand, to bond together thesheets forming the self-sealing valve and to bond them to the sheetsforming the cushion, and, on the other hand, to firmly attach the sheetsconstituting the guiding tabs to the cushion. It will be noted that thebonding line 212 a′ has a width markedly greater than that of the singlebonding line 212 a. This allows the possible inscription, within thebonding line 212 a′, of a mark or of any specification relating to thecushion.

The inflatable cushions 100 shown in FIGS. 16, 17, 18, 19 and 20, canthemselves also include, if necessary, a self-sealing inflating valve ina corner, according to the embodiments shown more particularly in FIGS.7, 23, 24 and 25.

In each instance in the above disclosure, where a bond is disclosed,this bond can be made using a radiation curable adhesive (or a blend ofradiation curable adhesives) which can be applied by any suitable means,such as coating, printing, etc., manually or by machine, in a continuousor discontinuous fashion, randomly or in a predetermined pattern,geometry, or profile, to one or both of the relevant surfaces that areto be adhered together.

Radiation Curable Adhesives

Radiation curable adhesives useful in place of heat seals can beselected based on cationic, free radical, and hybrid chemistries.Radiation curable adhesives offer much faster production speeds thanconventional heat seal processes. They can be used to construct avariety of adhesive junctions that can replace heat seals. Becauseradiation curable adhesives can be applied via traditional coatingprocesses, the options for specific shapes or geometries are vast andallow patterns not possible with heat seals, in a fast, continuous,laminating and curing process.

Radiation curable adhesives offer the advantage of bonding films withcontrollable bond strengths that can be moderate such as for tacking ortamper evident applications to very high with substrate destructionbefore bond failure. Bond strengths also can be controlled throughformulation and dose from low to high bond strength.

Radiation curable pressure sensitive adhesives are available withcontrolled tack and bond strength that allow easy removable, reclosableor permanent bonds along with improved properties such elevatedtemperature resistance not possible with thermoplastic type adhesives.

The radiation curable adhesive can be applied by flexographic,rotogravure, rotoscreen, ink jet, roll coating and other dispensingmethods.

This approach offers several advantages over the currently used heatsealing process that includes allowing complex patterns to be printed onwide web in any desired cushion pattern. The printing process can allowhigh throughput of about 200 fpm.

The adhesive beneficially can rapidly form strong bonds to the film,web, or other substrate on which it is applied. It is desirable that theradiation curable adhesive have the following characteristics as shownin Table 1. TABLE 1 Desirable Adhesive Characteristic Radiation CurableAdhesives No/low volatile organic compounds (VOC's), Typically no VOC'sused. Diluents if used, (no solvents), crosslink into polymer networkApplication/printing flexibility Has capability to be applied by variousprinting processes such as flexo, gravure, roto- screen, ink jet andother dispensing methods. Printed adhesive pattern can be immediately UVadhesives can be immediately laminated laminated and cured in-line as arapid continuous and UV light cured as continuous operation. in-lineprocesses. UV curing process can often be carried out at 500 to 800 fpm.The curing equipment has a low foot print and Much lower spacerequirements compared to can be retrofitted to existing laminationlines. drying tunnels. UV light irradiators are available that are lessthan 12 inches wide. Power supplies also have low space requirements.Rapid development of full cured properties. Cationic systems reach fullcured properties in hours. Fully cured properties reached in secondswith radical type system Handling and storage ease. Typically 1 partthermoset type system and storage stable, even when left on applicationequipment. Not distort film Temperature sensitive substrates can be usedwith commercially available systems. Low temperature curing with properengineering controls.

The surface of the film, web, or other substrate on which the radiationcurable adhesive is applied can be corona pre-treated by standard coronatreatment techniques.

A low adhesive viscosity is beneficial for room temperature applicationif a flexographic printing method is employed, but application of aradiation curable adhesive at elevated temperatures is also possible. Insome cases, matching of the radiation curable adhesive formulation tothe film, web, or other substrate on which the radiation curableadhesive is to be applied can be beneficial.

Film substrates must be at least partially UV light transparent for freeradical type chemistries, where UV light is used as the radiation type,since the adhesive is cured through the film, although there arecommercial processes based on UV cationic type chemistry where theadhesive is initiated just before the film is laminated.

For example, the adhesive systems are formed or derived fromradiation-curable (i.e., radiation-polymerizable) components. Suchsystems have the ability to change from a fluid phase to a highlycross-linked or polymerized solid phase by means of a chemical reactioninitiated by a radiation energy source, such as ultra-violet (“UV”)light or electron beam (“EB”) or other ionizing radiation. Thus, thereactants of the radiation-curable adhesive systems are “cured” byforming new chemical bonds under the influence of radiation.

Radiation-curable adhesive systems or formulations that are cured by afree radical mechanism typically include: i) monomers (e.g.,low-viscosity monomers or reactive “diluents”) capable of polymerizationby free radical mechanism, ii) oligomers/prepolymers (e.g., acrylates)capable of polymerization by free radical mechanism, and optionally iii)other additives, such as non-reactive plasticizing diluents.Radiation-curable adhesive systems that are cured by UV light alsoinclude one or more photoinitiators. Radiation-curable radical adhesivesystems curable by electron beam (EB) radiation do not require aphotoinitiator, and may therefore be free of photoinitiator. Together,these monomers and oligomers/prepolymers may be grouped as “reactants.”

Reactive (meth)acrylate diluents include, but are not limited to,trimethylolpropane triacrylate, hexanediol diacrylate, 1,3-butyleneglycol diacrylate, diethylene glycol diacrylate, 1,6-hexanedioldiacrylate, neopentyl glycol diacrylate, polyethylene glycol 200diacrylate, tetraethylene glycol diacrylate, triethylene glycoldiacrylate, pentaerythritol tetraacrylate, tripropylene glycoldiacrylate, ethoxylated bisphenol-A diacrylate, propylene glycolmono/dimethacrylate, trimethylolpropane diacrylate,di-trimethylolpropane tetraacrylate, triacrylate of tris(hydroxyethyl)isocyanurate, dipentaerythritol hydroxypentaacrylate, pentaerythritoltriacrylate, ethoxylated trimethylolpropane triacrylate, triethyleneglycol dimethacrylate, ethylene glycol dimethacrylate, tetraethyleneglycol dimethacrylate, polyethylene glycol-200 dimethacrylate,1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate,polyethylene glycol-600 dimethacrylate, 1,3-butylene glycoldimethacrylate, ethoxylated bisphenol-A dimethacrylate,trimethylolpropane trimethacrylate, diethylene glycol dimethacrylate,1,4-butanediol diacrylate, diethylene glycol dimethacrylate,pentaerythritol tetramethacrylate, glycerin dimethacrylate,trimethylolpropane dimethacrylate, pentaerythritol trimethacrylate,pentaerythritol dimethacrylate, pentaerythritol diacrylate, aminoplast(meth)acrylates, and acrylated oils such as linseed, soya, and castoroils. Other polymerizable compounds that can be used include(meth)acrylamides, maleimides, vinyl acetate, vinyl caprolactam,polythiols, vinyl ethers and the like. Monoacrylates such as cyclohexylacrylate, isobornyl acrylate, lauryl acrylate and tetrahydrofurfurylacrylate and the corresponding methacrylates are also operable asreactive diluents as well as (meth)acrylate oligomers such as epoxyacrylates, urethane acrylates, and polyester or polyether acrylates.

Useful oligomers/prepolymers include resins having acrylatefunctionality, such as epoxy acrylates, polyurethane acrylates, andpolyester acrylates. Exemplary oligomers and prepolymers include(meth)acrylated epoxies, (meth)acrylated polyesters, (meth)acrylatedurethanes/polyurethanes, (meth)acrylated polyethers, (meth)acrylatedpolybutadiene, aromatic acid (meth)acrylates, and (meth)acrylatedacrylic oligomers and the like.

If the radiation-curable adhesive are cured by free radical mechanismand formulated for curing by exposure to UV-light, then the adhesiveincludes one or more photoinitiators. Photoinitiators for free radicalcuring are well known to those skilled in the art. Specific examplesinclude, but are not limited to, the benzoin alkyl ethers, such asbenzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether andbenzoin isobutyl ether. Another class of photoinitiators are thedialkoxyacetophenones exemplified by 2,2-dimethoxy-2-phenylacetophenone,i.e., IRGACURE®651 (Ciba-Geigy) and 2,2-diethoxy-2-phenylacetophenone.Still another class of photoinitiators are the aldehyde and ketonecarbonyl compounds having at least one aromatic nucleus attacheddirectly to the carboxyl group. These photoinitiators include, but arenot limited to benzophenone, acetophenone, o-methoxybenzophenone,acetonaphthalenequinone, methyl ethyl ketone, valerophenone,hexanophenone, alpha-phenyl-butyrophenone, p-morpholinopropiophenone,dibenzosuberone, 4-morpholinobenzophenone, 4′-morpholinodeoxybenzoin,p-diacetylbenzene, 4-aminobenzophenone, 4′-methoxyacetophenone,benzaldehyde, alpha-tetralone, 9-acetylphenanthrene,2-acetylphenanthrene, 10-thioxanthenone, 3-acetylphenanthrene,3-acetylindone, 9-fluorenone, 1-indanone, 1,3,5-triacetylbenzene,thioxanthen-9-one, xanthene-9-one, 7-H-benz[de]-anthracen-7-one,1-naphthaldehyde, 4,4′-bis(dimethylamino)-benzophenone, fluorene-9-one,1′-acetonaphthone, 2′-acetonaphthone, 2,3-butedione, acetonaphthene,benz[a]anthracene 7.12 diene, etc. Phosphines such as triphenylphosphineand tri-o-tolylphosphine are also operable herein as photoinitiators.The photoinitiators or mixtures thereof are usually added in an amountranging from 0.01 to 5% by weight of the total composition.

Radiation-curable adhesive systems or formulations that are UV cured bycationic mechanism typically include: i) monomers, oliogomers and/orpolymers that are capable of cationic polymerization such as but notlimited to aliphatic and/or cycloaliphatic epoxides and/or vinyl ethers,many of which are known to one skilled in the art, ii) one or morecationic photoinitiators that are known to one skilled in the art asonium salts, and optionally iii) polyols (organic compounds that containhydroxyl functionality that are capable of adding to protonated epoxide)and other additives, such as non-reactive plasticizing diluents. Thereare many epoxides and vinyl ethers that are suitable. but cycloaliphaticepoxides (containing at least one epoxide group) are preferred. Examplesinclude but are not limited to epoxides sold under the CYRACURE® (DowChemical) or UVACURE™ (UCB Chemical) trade names. The cycloaliphaticepoxides with cationic photoinitiator(s) may be used alone or incombination with polyols at varying concentrations. Examples of polyolsinclude polycaprolactone type polyols but other polyols may be used.

UV cationic onium type photoinitiators useful for UV curable cationicadhesives are well known by one skilled in the art. U.S. Pat. Nos.4,407,759 and 4,417,061, both incorporated herein by reference in theirentirety, are useful for describing onium type photoinitiators of whichthere are many types commercially available. Examples of commerciallyavailable onium type photoinitiators include but are not limited toSarCAT® CD-1012 and KI-85™ from Sartomer.

Another type of UV adhesive that has found utility are, but are notlimited to, mixtures of free radical UV adhesives and cationic UVadhesives. They are sometimes called hybrid systems because they havecomponents that have been previously described as useful in free radicalUV adhesives, and components that have been previously described asuseful in cationic UV adhesives. These hybrid adhesives cure by freeradical and cationic mechanisms when exposed to light useful forinducing polymerization. Some onium salt cationic photoinitiators suchas iodonium compounds can be optionally used in combination with freeradical type photoinitiators such as 2-isopropyl thioxanthone to improvethe UV light cationic initiation. An example of this type of mixed UVcationic photoinitiator system include but not limited to UV 9380 (GESilicones).

Although the radiation cured adhesive layer of the various embodimentsis typically shown as extending the full width or length of a givenarticle, alternatively the radiation curable adhesive can be appliedalong a selected region of the article, in a continuous or discontinuousmanner or pattern as desired, in either the longitudinal direction orwith respect to the article width.

Other radiation curable adhesives that cure by a free radical mechanismcan be used in connection with the present invention, of which anexample is listed in Table 3, but are not preferred. TABLE 3 MaterialMaterial Name Supplier type/function parts TMP-TA ™ UCB Chemicals freeradical 46.4 Corp crosslinker RICON ™ 3801 Sartomer acrylatedpolybutadiene 46.2 crosslinker ODAB ™ First Chemical Liquid aminesynergist 1.8 Corp. IRGACURE ® 819 Ciba Phosphine oxide 0.4 typefree-radical photoinitiator LTX ™ First Chemical liquid thioxanthone0.92 Corp. type free-radical photoinitiator BD-1 ™ First Chemical Blendof free-radical 2.78 Corp. photoinitiator

The ratios and amounts of the components used in E and F can be variedby one skilled in the art.

Other cationic photoinitiators can be used as the “E” UV adhesive (e.g.CD1012).

Other free radical photoinitiators can be used as the “F” adhesive.

The adhesives can be storage stable when properly stored.

The adhesives can have viscosities that allow rapid and easy applicationat room temperature.

An electron beam (EB) is one useful form of radiation, although UV-lightradiation can also be used. The radiation source for an EB system isknown as an EB generator.

Two factors are important in considering the application of EBradiation: the dose delivered and the beam penetration. The dose ismeasured in terms of quantity of energy absorbed per unit mass ofirradiated material; units of measure in general use are the megarad(Mrad) and kiloGray (kGy). The depth of penetration by an electron beamis directly proportional to the energy of the accelerated electronsimpinging on the exposed material (expressed as kiloelectron volts,keV).

Regardless of the radiation source, the radiation dose will besufficient and effective to cure the radiation curable adhesive.

Useful radiation dosages can range from e.g. 0.2 to 10 Mrads. Usefulenergies for the EB can range from 30 to 250 keV.

Useful EB generation units include those commercially available fromAmerican International Technologies sold under the trademark MINI-EB™(these units have tube operating voltages from about 30 to 70 keV) andfrom Energy Sciences, Inc. sold under the trademark EZ CURE™ (theseunits have operating voltages from about 70 to about 110 keV). EBgeneration units typically require adequate shielding, vacuum, and inertgassing, as is known in the art. If the processing techniques employedallow for the use of a low oxygen environment, the coating andirradiation steps beneficially occur in such an atmosphere. A standardnitrogen flush can be used to achieve such an atmosphere.

Radiation Curable Adhesive Thickness

The radiation curable adhesive is applied in a thickness that once curedis effective to provide the desired bond strength. Useful averagethicknesses of radiation curable adhesive include, without limitation,from 0.1 to 12 micrometers. An adhesive thickness of more than 12micrometers, at least in parts of the bond in certain applications, suchas the bond around a self sealing valve (see FIG. 20 to 25) may bebeneficial depending on the total thickness of the valve. In the case ofan intermittent, discontinuous adhesive layer, the average thickness of0.1 to 12 micrometers is directed to the regions or portions thatactually contain the adhesive. Other average thicknesses that may beuseful depending upon the particular application include from 0.5 to 10micrometers, such as 1 to 8, 2 to 7 and 3 to 6 micrometers.

The radiation cured adhesive, once it forms a bonding layer or regionwithin an article, should be able to withstand normal packing,distribution, and handling.

The radiation curable adhesive can be used as a bonding medium for manydifferent package formats that traditionally rely on heat sealing orother sealing mechanisms. Examples include VFFS packages, HFFS packages,lidded trays or cups, pouches, bags, or other like packages.

Useful package configurations for use in connection with the presentinvention include end-seal bag, a side-seal bag, an L-seal bag (e.g.,sealed across the bottom and along one side with an open top), or apouch (e.g., sealed on three sides with an open top). Such bagconfigurations are known to those of skill in the art. See, for example,U.S. Pat. No. 5,846,620 issued Dec. 8, 1998 to Compton, which isincorporated herein in its entirety by reference. Additionally, lapseals may be employed, in which the inside region of the film is bondedto an outside region of the film. In each of these formats and thosedisclosed herein, any or all of the seals traditionally formed by heator alternative sealing technologies can be replaced by a radiation curedadhesive bond. Those skilled in the art will also appreciate that thepresent invention can be used in conjunction with traditional heatsealing or other sealing methods. Thus, e.g. a bag, thermoformedcontainer, film/foam composite; or inflatable packaging cushion, couldhave one or more radiation cured adhesive bonds, as well as one or moreheat seals.

Suitable food products for packaging by the present method include fattyfoods (e.g., meat products, cheese products), aqueous foods (e.g.,produce and some soups), and dry food (e.g., cereal, pasta). Examples ofmeat products that may be packaged include, poultry (e.g., turkey orchicken breast), bologna, braunschweiger, beef, pork, lamb, fish, andwhole muscle products such as roast beef, and other red meat products.Examples of produce or vegetables that may be packaged include cut anduncut lettuce, carrots, radish, and celery. The food product may besolid, solid particles, dry, fluid, or a combination thereof.

A film can also be wrapped around a product and bonded together asdescribed herein to form a package enclosing the product. If the film isa heat-shrinkable film, the resulting bag or other container can beheated to shrink the film around the product.

The above descriptions are those of various embodiments and examples ofthe invention. Various alterations and changes can be made withoutdeparting from the spirit and broader aspects of the invention asdefined in the claims.

Any reference to an item in the disclosure or to an element in the claimin the singular using the articles “a,”, “an,” “the,” or “said” is notto be construed as limiting the item or element to the singular unlessexpressly so stated.

Any numerical values recited herein include all values from the lowervalue to the upper value in increments of one unit provided that thereis a separation of at least 2 units between any lower value and anyhigher value. As an example, if it is stated that the amount of acomponent, or a value of a process variable and the like is, forexample, from 1 to 90, such as 20 to 80, such as 30 to 70, it isintended that values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 andthe like, are expressly enumerated in this specification. For valueswhich are less than one, one unit is considered to be 0.0001, 0.001,0.01 or 0.1 as appropriate. These are only examples of what isspecifically intended and all possible combinations of numerical valuesbetween the lowest value and the highest value enumerated are to beconsidered to be expressly stated in this application in a similarmanner.

1. A bag comprising: a) a first panel; b) a second panel; c) first andsecond layflat side edges; d) a bottom edge; and e) a bag mouth; whereinat least one of the first and second layflat side edges, and the bottomedge, comprises a radiation cured adhesive layer bonding the first andsecond panels together.
 2. The bag of claim 1 wherein the bag panelseach comprise a film having an oxygen barrier layer, and a bondinglayer.
 3. The bag of claim 1 wherein the average thickness of theradiation cured adhesive layer is from 0.1 to 12 micrometers.
 4. The bagof claim 1 wherein the radiation cured adhesive forms a pattern.
 5. Thebag of claim 1 wherein the radiation cured adhesive forms adiscontinuous layer.
 6. A thermoformed container comprising: a) aforming web, the forming web comprising a polymeric material; b) asubstantially non-forming web comprising a polymeric material; and c) aradiation cured adhesive layer disposed between and bonding at leastportions of the forming web and the substantially non-forming web. 7.The thermoformed container of claim 6 wherein the forming web and thesubstantially non-forming web each comprise a film having an oxygenbarrier layer, and a bonding layer.
 8. The thermoformed container ofclaim 6 wherein the average thickness of the radiation cured adhesivelayer is from 0.1 to 12 micrometers.
 9. The thermoformed container ofclaim 6 wherein the radiation cured adhesive layer forms a pattern. 10.The thermoformed container of claim 6 wherein the radiation curedadhesive forms a discontinuous layer.
 11. A film/foam compositecomprising: a) a thermoplastic film comprising a polymeric material; b)a polymeric foam sheet; and c) a radiation cured adhesive layer disposedbetween and bonding at least portions of the thermoplastic film and thepolymeric foam sheet.
 12. The film/foam composite of claim 11 whereinthe thermoplastic film comprises a layer comprising a polyolefinicmaterial.
 13. The film/foam composite of claim 11 wherein the averagethickness of the radiation cured adhesive layer is from 0.1 to 12micrometers.
 14. The film/foam composite of claim 11 wherein theradiation cured adhesive layer forms a pattern.
 15. The film/foamcomposite of claim 11 wherein the radiation cured adhesive forms adiscontinuous layer.
 16. An inflatable packaging cushion comprising aplurality of flexible plastic sheets bonded together in the region oftheir edges, wherein a radiation cured adhesive layer bonds at least aportion of the flexible plastic sheets together.
 17. The inflatablepackaging cushion of claim 16 wherein the flexible plastic sheets eachcomprise a layer comprising a polyolefinic material.
 18. The inflatablepackaging cushion of claim 16 wherein the average thickness of theradiation cured adhesive is from 0.1 to 12 micrometers.
 19. Theinflatable packaging cushion of claim 16 wherein the radiation curedadhesive forms a pattern.
 20. The inflatable packaging cushion of claim16 wherein the radiation cured adhesive forms a discontinuous pattern.